You usually set up a system where you have constant feedback, like daily stand ups, weekly ( or bi-weekly) sprints etc. before closing out an issue have the devs demo the feature so it’s not based purely on word of mouth.

Personally: I would advice getting lunch with them and getting to know them better. Set up a 1:1 if lunch isn’t possible. Everyone likes honest feedback, or at least a chance to talk about their difficulties in getting tasks done.